Mesoscale Precipitation Discussion 0787
NWS Weather Prediction Center College Park MD
417 AM EDT Fri Sep 07 2018

Areas affected...Southern Cap Rock/Northwest TX...Western to
Central OK...

Concerning...Heavy rainfall...Flash flooding possible

Valid 070816Z - 071230Z

SUMMARY...Slow moving/highly efficient showers producing up to
2"/hr totals capable of localized flash flooding.

DISCUSSION...Inconspicuous and highly sheared convection are
generally scattered across the Cap Rock into western OK on the
10.3um IR imagery from GOES-16.  Cells are highly sheared given
proximity of strengthening upper level jet across NM to W KS with
50kt core over the NW TX/OK panhandles while flow between 8-4H is
nearly zero.  The area of concern lies within the SW edge of
enhanced deep moisture along deformation zone where mean mixing
ratios are 16 kg/kg and total PWATs in the range of 2".  Cells
across the CAP Rock of Northwest TX are further west into the
moisture gradient yet have access to sufficient moisture for heavy
warm cloud rain process generation.   Mst flux/convergence is
supported at the surface to boundary layer with 10-15 enhanced
northerly winds with the core generally surging south along 100W
providing sufficient convergence with slower winds/mass upstream. 
This is maintaining convection surprisingly well given the
remaining weaker flow aloft, especially across TX.  being on the
southeast side of the jet is supporting sufficient evacuation
aloft as well to prolong updrafts with tilt to not collapse back
on themselves with rainfall production.  As such longer duration
of highly efficient rainfall supports rates in excess of 2"/hr, as
supported by KHBR recent one hour total over 2.25".

While the cells are not numerous in coverage or broad in updraft
width, these totals are capable of producing localized flash
flooding conditions.   Further strengthening of the upper level
jet and maintaining enhanced northerly surface flow will support
continued threat through the late overnight into early morning
across Western OK with some weak eastward propagation possible. 
Likewise across TX...the convergence along the western
side/anticyclonic rotor of the northerly surface jet should
maintain convergence as cell propagate south and SSW over the next
few hours. 

Gallina

ATTN...WFO...LUB...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...

LAT...LON   36779846 36769751 36099733 35099735 34309767
            33439897 33040093 33500199 34620177 34719961
            36009890